In most zombie apocalypse scenarios, only humans are converted into the shambling undead. And…
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There's also the simple effects of the elements.

Wind and rain will eventually take it's toll on any kind of undead, and either nullify them, or reduce their effectiveness. Similarly, winter weather and extreme heat would likely nullify a zombie. The cold, because it'd damage the tissues and cause it to crack or even shatter, and the heat because it'd cause tissues to dry out and become fragile.

The scientific POV might suggest that a zombie who does freeze might even die if the brain freezes through, the ice crystals that form in any water in the brain tissue would expand and destroy the CNS. I still wouldn't want to take a chance though, and just blow zombicle away with my shot gun or in this case use an ice pick.